1 //===- lib/ReaderWriter/FileArchive.cpp -----------------------------------===//
2 //
3 //                             The LLVM Linker
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "lld/Core/ArchiveLibraryFile.h"
11 #include "lld/Core/File.h"
12 #include "lld/Core/LLVM.h"
13 #include "lld/Core/Reader.h"
14 #include "llvm/ADT/StringRef.h"
15 #include "llvm/Object/Archive.h"
16 #include "llvm/Support/Debug.h"
17 #include "llvm/Support/Format.h"
18 #include "llvm/Support/MemoryBuffer.h"
19 #include "llvm/ADT/STLExtras.h"
20 #include "llvm/Object/Error.h"
21 #include "llvm/Support/ErrorOr.h"
22 #include "llvm/Support/FileSystem.h"
23 #include "llvm/Support/raw_ostream.h"
24 #include <memory>
25 #include <set>
26 #include <string>
27 #include <system_error>
28 #include <unordered_map>
29 #include <utility>
30 #include <vector>
31 
32 using llvm::object::Archive;
33 
34 namespace lld {
35 
36 namespace {
37 
38 /// \brief The FileArchive class represents an Archive Library file
39 class FileArchive : public lld::ArchiveLibraryFile {
40 public:
41   FileArchive(std::unique_ptr<MemoryBuffer> mb, const Registry &reg,
42               StringRef path, bool logLoading)
43       : ArchiveLibraryFile(path), _mb(std::shared_ptr<MemoryBuffer>(mb.release())),
44         _registry(reg), _logLoading(logLoading) {}
45 
46   /// \brief Check if any member of the archive contains an Atom with the
47   /// specified name and return the File object for that member, or nullptr.
48   File *find(StringRef name) override {
49     auto member = _symbolMemberMap.find(name);
50     if (member == _symbolMemberMap.end())
51       return nullptr;
52     Archive::Child c = member->second;
53 
54     // Don't return a member already returned
55     ErrorOr<StringRef> buf = c.getBuffer();
56     if (!buf)
57       return nullptr;
58     const char *memberStart = buf->data();
59     if (_membersInstantiated.count(memberStart))
60       return nullptr;
61     _membersInstantiated.insert(memberStart);
62 
63     std::unique_ptr<File> result;
64     if (instantiateMember(c, result))
65       return nullptr;
66 
67     File *file = result.get();
68     _filesReturned.push_back(std::move(result));
69 
70     // Give up the file pointer. It was stored and will be destroyed with destruction of FileArchive
71     return file;
72   }
73 
74   /// \brief parse each member
75   std::error_code
76   parseAllMembers(std::vector<std::unique_ptr<File>> &result) override {
77     if (std::error_code ec = parse())
78       return ec;
79     llvm::Error err;
80     for (auto mf = _archive->child_begin(err), me = _archive->child_end();
81          mf != me; ++mf) {
82       std::unique_ptr<File> file;
83       if (std::error_code ec = instantiateMember(*mf, file)) {
84         // err is Success (or we wouldn't be in the loop body) but we can't
85         // return without testing or consuming it.
86         consumeError(std::move(err));
87         return ec;
88       }
89       result.push_back(std::move(file));
90     }
91     if (err)
92       return errorToErrorCode(std::move(err));
93     return std::error_code();
94   }
95 
96   const AtomRange<DefinedAtom> defined() const override {
97     return _noDefinedAtoms;
98   }
99 
100   const AtomRange<UndefinedAtom> undefined() const override {
101     return _noUndefinedAtoms;
102   }
103 
104   const AtomRange<SharedLibraryAtom> sharedLibrary() const override {
105     return _noSharedLibraryAtoms;
106   }
107 
108   const AtomRange<AbsoluteAtom> absolute() const override {
109     return _noAbsoluteAtoms;
110   }
111 
112   void clearAtoms() override {
113     _noDefinedAtoms.clear();
114     _noUndefinedAtoms.clear();
115     _noSharedLibraryAtoms.clear();
116     _noAbsoluteAtoms.clear();
117   }
118 
119 protected:
120   std::error_code doParse() override {
121     // Make Archive object which will be owned by FileArchive object.
122     llvm::Error Err;
123     _archive.reset(new Archive(_mb->getMemBufferRef(), Err));
124     if (Err)
125       return errorToErrorCode(std::move(Err));
126     std::error_code ec;
127     if ((ec = buildTableOfContents()))
128       return ec;
129     return std::error_code();
130   }
131 
132 private:
133   std::error_code instantiateMember(Archive::Child member,
134                                     std::unique_ptr<File> &result) const {
135     ErrorOr<llvm::MemoryBufferRef> mbOrErr = member.getMemoryBufferRef();
136     if (std::error_code ec = mbOrErr.getError())
137       return ec;
138     llvm::MemoryBufferRef mb = mbOrErr.get();
139     std::string memberPath = (_archive->getFileName() + "("
140                            + mb.getBufferIdentifier() + ")").str();
141 
142     if (_logLoading)
143       llvm::errs() << memberPath << "\n";
144 
145     std::unique_ptr<MemoryBuffer> memberMB(MemoryBuffer::getMemBuffer(
146         mb.getBuffer(), mb.getBufferIdentifier(), false));
147 
148     ErrorOr<std::unique_ptr<File>> fileOrErr =
149         _registry.loadFile(std::move(memberMB));
150     if (std::error_code ec = fileOrErr.getError())
151       return ec;
152     result = std::move(fileOrErr.get());
153     if (std::error_code ec = result->parse())
154       return ec;
155     result->setArchivePath(_archive->getFileName());
156 
157     // The memory buffer is co-owned by the archive file and the children,
158     // so that the bufffer is deallocated when all the members are destructed.
159     result->setSharedMemoryBuffer(_mb);
160     return std::error_code();
161   }
162 
163   std::error_code buildTableOfContents() {
164     DEBUG_WITH_TYPE("FileArchive", llvm::dbgs()
165                                        << "Table of contents for archive '"
166                                        << _archive->getFileName() << "':\n");
167     for (const Archive::Symbol &sym : _archive->symbols()) {
168       StringRef name = sym.getName();
169       ErrorOr<Archive::Child> memberOrErr = sym.getMember();
170       if (std::error_code ec = memberOrErr.getError())
171         return ec;
172       Archive::Child member = memberOrErr.get();
173       DEBUG_WITH_TYPE("FileArchive",
174                       llvm::dbgs()
175                           << llvm::format("0x%08llX ",
176                                           member.getBuffer()->data())
177                           << "'" << name << "'\n");
178       _symbolMemberMap.insert(std::make_pair(name, member));
179     }
180     return std::error_code();
181   }
182 
183   typedef std::unordered_map<StringRef, Archive::Child> MemberMap;
184   typedef std::set<const char *> InstantiatedSet;
185 
186   std::shared_ptr<MemoryBuffer> _mb;
187   const Registry &_registry;
188   std::unique_ptr<Archive> _archive;
189   MemberMap _symbolMemberMap;
190   InstantiatedSet _membersInstantiated;
191   bool _logLoading;
192   std::vector<std::unique_ptr<MemoryBuffer>> _memberBuffers;
193   std::vector<std::unique_ptr<File>> _filesReturned;
194 };
195 
196 class ArchiveReader : public Reader {
197 public:
198   ArchiveReader(bool logLoading) : _logLoading(logLoading) {}
199 
200   bool canParse(file_magic magic, MemoryBufferRef) const override {
201     return magic == llvm::sys::fs::file_magic::archive;
202   }
203 
204   ErrorOr<std::unique_ptr<File>> loadFile(std::unique_ptr<MemoryBuffer> mb,
205                                           const Registry &reg) const override {
206     StringRef path = mb->getBufferIdentifier();
207     std::unique_ptr<File> ret =
208         llvm::make_unique<FileArchive>(std::move(mb), reg, path, _logLoading);
209     return std::move(ret);
210   }
211 
212 private:
213   bool _logLoading;
214 };
215 
216 } // anonymous namespace
217 
218 void Registry::addSupportArchives(bool logLoading) {
219   add(std::unique_ptr<Reader>(new ArchiveReader(logLoading)));
220 }
221 
222 } // namespace lld
223